This invention relates in general to sealing devices and more particularly to seals for antifriction bearings.
Rib-mounted bearing seals are highly compact and extend the length of a bearing only a nominal amount, if at all. They are widely used in connection with tapered roller bearings. The typical rib-mounted seal for a tapered roller bearing has a case which is pressed over the thrust rib of the bearing cone and an elastomeric seal element which is bonded to the case. The seal element possesses a primary lip which bears against the front face of the bearing cup and a dust lip which contacts the surface of the housing bore into which the cup fits. This type of seal forms the subject matter of U.S. Pat. No. 3,006,701 issued Oct. 31, 1961.
While rib-mounted seals possess substantial advantages, primarily due to the high degree of compactness, such seals also increase the cost of the overall bearing installation. This increase in cost resides in the fact that the outside diameter of the thrust rib and the inside diameter of the seal case must be held to within close tolerances. Indeed, the diameter of these surfaces must be such that the press fit which exists between the seal case and thrust rib is between 0.001 and 0.004 inch tight. A tighter press fit causes the seal case to bellmouth, that is flare outwardly at its end (FIG. 1), and this puts less surface area of the seal case in contact with the thrust rib. Retention is therefore reduced. Bell mouthing furthermore inclines the seal element (FIG. 1) such that the sealing lip is withdrawn from the cup front face and may not bear against that face with adequate force. A lesser press fit likewise reduces the retention. While the seal case may be stamped with considerable precision, the close tolerances on the thrust rib are usually obtained by grinding the outside diameter of the thrust rib, and this is an expensive procedure.